1. Field of the Invention
This invention relates to leather products and more specifically to leather beading line for use in such applications as stringing beads or necklaces.
2. Prior Art
The art of leather shaping has been relatively dormant for the past half century, as is evident from a search of the patent art related to that subject. In that earlier era the end use of the leather products was related to harnesses and other horse gear. The thickness of the material being treated and the thickness or diameter of the resultant product was great relative to the diameter of the end product contemplated here. As a result, ridges and other imperfections in the surface could be tolerated in the products of the prior era while still permitting the intended end use of the product. The primary techniques utilized to obtain desired cross-sectional shapes were cutting, rolling and drawing. Examples of such techniques are set forth in U.S. Pat. Nos. 115,949 (Foster) and 899,860 (Coleman). Other U.S. Pats. such as No. 162,762 (Osborne) and No. 950,096 (Driscoll) show the use of split, leather-forming dies.
Beginning with flat lace of substantially rectangular cross-section, there is no way of obtaining the desired product by cutting. Cutting is appropriate only if the starting material is of substantially square cross-section. Such material might be obtained by cutting the lace from thicker and older hides. However, older hides are more porous, grainy and weaker than the younger, thinner calf hides, and are therefore not suitable for obtaining the product according to the present invention. Moreover, cutting produces a waste material which is not created with my invention since my invention, like the process of rolling, involves not the taking away of material but rather the reshaping of it. Indeed, if the aforementioned calf lace were to be cut, say to conform in width to the diameter of the beading line of this invention the resulting line would still be unlike the beading line of this invention in that the cut line would remain consistently flat and, moreover, would be weakened by the loss of material. Finally, any analogous product obtained from older cow hides by a process of cutting would have the additional disadvantages of exhibiting a relatively rough external surface texture and would be either extremely weak in tensile strength or else would be of much greater diameter than the product of my invention, or both. A larger diameter severely restricts the use of such materials in bead stringing, whereas our product can be used with a great variety of bead sizes, and bead stringing is the primary intended use of my claimed end product.
Further, the various methods of rolling leather round are unacceptable because either they limit the length of the leather strips that are obtainable, or they require as starting material leather strips of substantially square cross section, or both. They may also be incapable of producing leather string with a diameter as small as is contemplated here. For even with the method in which the starting material is rolled through an orifice created between the appropriately shaped surfaces of two rollers, and even if one of these rollers is fitted with suitable flanges extending into the indentation of the second roller so as to keep the material being rolled from spreading laterally between the flat and contiguous surfaces of the rollers, there exists a problem, namely, the formation of a longitudinal ridge or "flashing" along the length of the finished product. While such flashing is not objectionable where the product itself is large in diameter, as in harnesses, it is objectionable in smaller-diameter products, such as the beading line contemplated here, which line may have a final diameter of only about 3/64 inch. Furthermore, the layered material may catch in the joint between the two rollers whereupon there is great risk of the material's being cut by the flanges of one roller pressing against the walls of the other roller, and therefore, there is a great danger of leather rupture and breakage. Also, there is a lack of uniform pressure around the material, a problem not faced with a closed-die drawing process.
Similar difficulties arise in drawing the lace through split dues, a method that, historically, was rejected in favor of the method involving rollers. Here, too, there is the aformentioned flashing, lack of uniform pressure and danger of breakage when the material catches in the joints of the split die. Breakage raises the cost of the end product because production time is lost and shortened lengths of saleable final product are obtained.
Therefore, it is a primary object of this invention to provide a process, apparatus for performing that process and the product of that process and apparatus, all of which are free from significant surface discontinuities.
It is a still further object of this invention to provide a process which produces from leather lacing which is rectangular in cross-section a thin, strong, pliable beading line which is small and consistent in diameter over its length.
It is an additional object of this invention to provide a leather beading line material which is smooth, circular in cross-section, strong and easily utilized in the stringing of beads for necklaces or the like.